When handling a liquid indoors, usually a sheet having a capacity to absorb or soak up water (hereinafter referred to as a “water absorbent sheet”) is laid on an object which would be suffered from being wet such as a floor or a table for protecting it from the water. However, such aim will not be achieved when a liquid amount to be absorbed exceeds the capacity of the water absorbent sheet or when the water absorbent sheet shifts from the proper position. Typical cases of such shifts are that a pet moves the water absorbent sheet during feeding or excreting thereon. The water absorbent sheet which is broken by the pet comes upon the same situation in which the liquid amount to be absorbed exceeds the capacity thereof. Toilet mats for a pet are proposed by Patent Literature 1 and Patent Literature 2 for proactively counter the above cases.
As shown in FIG. 16 and FIG. 17, the toilet mat for a pet proposed by Patent Literature 1 is used in a state in which a toilet sheet for a pet is laid on an upper surface thereof. The toilet mat for a pet 1001 includes a main body formed in almost a rectangular shape, and a pair of fixtures 1011a and 1011b for retaining the toilet sheet for a pet 1002 on the main body. The main body is made with a material, preferably has water repellency, which is well durable and easy to change the shape for convenience of carrying. Provided with are magnets 112 to the main body, and magnets 111 to the fixtures 1011a and 1011b. 
Installation of the toilet sheet for a pet 1002 in the toilet mat for a pet 1001 is made in a manner below. After the toilet sheet for a pet (hereinafter referred to as a “toilet sheet”) 1002 is laid on the upper surface of the main body, the fixtures 1011a and 1011b are located in the positions over the laid sheet 1002 so that the magnets 111 position above the magnets 112. Then, the fixtures 1011a and 1011b are let down toward the main body so that the magnets 111 and 112 stick to each other. An attraction force working between the magnets 111 and 112 generates a frictional force between the toilet sheet 1002 and the magnets 111 and 112. The toilet sheet 1002 is fixed on and retained by the toilet mat for a pet 1001 by the frictional force. The toilet sheet 1002 can be removed from the main body after the fixtures 1011a and 1011b are detached from the main body.
The fixtures 1011a and 1011b, when the magnets 111 and 112 are not provided therein, press the toilet sheet 1002 against the toilet mat for a pet 1001 by the self weight thereof, causing the frictional force between the toilet sheet 1002 and the fixtures 1011a and 1011b to fix the toilet sheet 1002 thereat. To prevent the toilet sheet 1002 from shifting due to the pet's motion, it is devised that the frictional force is increased by increasing the weight of the fixtures 1011a and 1011b to increase the fixing force of the toilet sheet 1002. When the magnets 111 and 112 are provided, it is devised to increase the magnetism thereof to increase the frictional force.
As shown in FIG. 18, a toilet mat for a pet 2001 (not shown) of Patent Literature 2 is used in a state in which a toilet sheet for a pet is laid on an upper surface thereof, as the toilet mat for a pet of Patent Literature 1 is. The toilet mat for a pet 2001 is constructed of at least four units of substrate 2002. The substrate 2002 includes peripheral walls 2004a to 2004d provided on a bottom on a perimeter of a rectangular planar shaped top plate 2003 so as to vertically extrude from a bottom side of the top plate 2003, and is made of a synthetic resin as a base for retaining the toilet sheet placed on the upper surface of the top plate 2003.
A sheet fixture 2010 fits in each of mounting holes 2009 bored with an oval sectional shape in each of four corners of the upper surface of the top plate 2003. Two oval shaped sheet fixtures 2010 are located on each diagonal line of the top plate 2003 such that the straightaway sections of the oval shape oppose to each other. The sheet fixture 2010 is provided with a cut portion 2011a formed from the upper surface to the bottom surface thereof. The toilet sheet placed on the upper surface of the top plate 2003 is retained onto the substrate 2002 such the four corners of the sheet are inserted in the cut portions 2011a. 
Four units of substrate 2002 are assembled into the toilet mat for a pet 2001 (not shown) by joining a first connection member 2005 or a second connection member 2006 provided in peripheral walls 2004a to 2004d to the first connection member 2005 or the second connection member 2006 provided in peripheral walls 2004a to 2004d of another discrete substrate 2002. The outermost four units of sheet fixture 2010 (cut portions 2011a), among sixteen units of sheet fixture 2010 available on the toilet mat for a pet 2001 comprised of four units of substrate 2002, retains the water absorbent sheet placed over the toilet mat for a pet 2001.